1. Field of the Invention
The present invention relates to a keyboard having a set of key-switch devices, and particularly it relates to a keyboard used as an input device of an electrical device.
2. Description of the Related Art
Japanese Unexamined Patent Publication (Kokai) No. 2002-216575 discloses a keyboard device having a seal member which can prevent liquid such as water from entering a contact part of each membrane switch even if the liquid is spilled from above a set of key-switch devices by mistake.
Japanese Utility Model Publication (Kokai) No. 5-2233 discloses a keyboard cover which can protect a keyboard against dust and the like, and allows a user to do a blind operation.
Further, Japanese Unexamined Patent Publication (Kokai) No. 1-231109 discloses a keyboard cover, which seals up a set of key-switch devices, but offers the same key stroke as that of a typical keyboard.
In the Patent Publication No. 2002-216575, an attempt to avoid the possibility of pressing a wrong key switch is made by disposing a key top under the seal member. However, the keyboard device has the following problems. The first is that the number of parts and the cost are increased because the keyboard device has a rubber spring for elastically urging each key top upward. The second is that the possibility of a user pressing a wrong key-switch device cannot be eliminated absolutely because the key-switch devices are covered with the seal member. In addition, it is not disclosed therein to illuminate the key-switch devices. The keyboard device also has a problem that the rubber spring for urging the key top upward blocks light from illuminating the key-switch devices.
Also, the Utility Model Publication No. 5-2233 discloses a cover for protecting a keyboard against dust. However, the structure of key-switch devices is still unknown, and it is not disclosed therein to illuminate the key-switch devices. Further, to allow a user to do a blind operation, the dustproof keyboard protection cover has a protrusion in a portion corresponding to the key-switch device of each home position. However, it just helps the user to distinguish the home position through the cover, and as to other key-switch devices, there is still the possibility of the user pressing a wrong key-switch device as in the case of the Patent Publication No. 2002-216575.
Also, the Patent Publication No. 1-231109 discloses a cover for protecting a keyboard against dust. However, the structure of key-switch devices is still unknown, and it is not disclosed therein to illuminate the key-switch devices. Further, the key-switch devices are covered with a seal member, and therefore there is the possibility of a user pressing a wrong key-switch device as in the cases of the Patent Publication No. 2002-216575 and Utility Model Publication No. 5-2233.